The present invention is concerned generally with a closure cap having a tamper-indicating band, and particularly to such a closure in which a plurality of flaps are provided on the tamper-indicating band for engaging an annular retaining bead on a container to retain the band on the container.
Closure caps of this type generally comprise a top panel with a cylindrical skirt depending from the periphery thereof. A tamper-indicating band is in some way frangibly connected to the open end of the skirt. The tamper-indicating band has retaining flaps which extend radially inwardly and towards the top panel to allow engagement under an annular retaining bead on a container. When the closure cap is removed from the container for the first time, for example by unscrewing, the flaps apply torque to the band and prevent the band from following the upper portion of the cap in its upwardly translational movement. The tamper-evident band is retained on the container as visible evidence that the container has already been opened.
Tamper-evident closure caps of this general type are well known within the art. For example, patent document U.S. Pat. No. 4,550,844 describes a tamper-evident band with a plurality of wedge-shaped tabs that contact a retaining bead on a container. The thicker outer portion of the tabs wedge against the container retaining bead to apply torque to the tamper-evident band and break frangible bridges which connect the band to the rest of the cap.
Closure caps of this type are generally moulded with the flaps connected to the bottom of the tamper-evident band from where they depend in such a way that they can hinge. Following moulding the flaps are then upturned before the closure is applied to the container and the flaps pass over the container retention bead with hinging movement. It is particularly important in closure caps of this type that the tamper-indicating band remains on the container as the upper portion of the cap is unscrewed. The design of the flaps is therefore preferably such that when an upwardly axial force is applied to the tamper-evident band the flaps do not flip back down to their as-moulded condition such that the band can pass back over the container retention bead. In addition, the flaps must be flexible enough to pass over the retention bead when the cap is first applied to the container. This could be achieved, for example, by the use of longer flaps.
Whilst strengthening of the flap, for example by increasing its thickness or its length, improves retention of the tamper-evident band on the container, this decreases the ability of the flap to pass over the retaining bead as the closure cap is applied to the container. In addition the amount of material used is increased and the dimensions of the container and closure cap within which the flaps can be used is more limited.
As an alternative to upturned flaps the use of ratchet arrangements to break tamper-evident bands is known, for example, from JP 08164960. However, the ratchets are moulded projecting radially inwardly and thus present problems with de-moulding and with application to a container neck.